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  <title>伪元素</title>
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    .d6 {
        width: 600px;
        background-color: crimson;
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    .d6::first-line {
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    .d6::first-letter {
      font-size: 2em;
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    .d6::before {
      content: "123";
    }
    .d6::after {
      content: "456";
    }
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  <div class="d6">This document describes how user agents determine the names and descriptions of accessible objects from web content languages. This information is in turn exposed through accessibility APIs so that assistive technologies can identify these objects and present their names or descriptions to users. Documenting the algorithm through which names and descriptions are to be determined promotes interoperable exposure of these properties among different accessibility APIs and helps to ensure that this information appears in a manner consistent with author intent.</div>
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